man/sd_id128_to_string.3

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   2 .TH "SD_ID128_TO_STRING" "3" "" "systemd 214" "sd_id128_to_string"
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  22 .SH "NAME"
  23 sd_id128_to_string, sd_id128_from_string \- Format or parse 128\-bit IDs as strings
  24 .SH "SYNOPSIS"
  25 .sp
  26 .ft B
  27 .nf
  28 #include <systemd/sd\-id128\&.h>
  29 .fi
  30 .ft
  31 .HP \w'char\ *sd_id128_to_string('u
  32 .BI "char *sd_id128_to_string(sd_id128_t\ " "id" ",\ char\ " "s" "[33]);"
  33 .HP \w'int\ sd_id128_from_string('u
  34 .BI "int sd_id128_from_string(const\ char\ *" "s" ",\ sd_id128_t\ *" "ret" ");"
  35 .SH "DESCRIPTION"
  36 .PP
  37 \fBsd_id128_to_string()\fR
  38 formats a 128\-bit ID as a character string\&. It expects the ID and a string array capable of storing 33 characters\&. The ID will be formatted as 32 lowercase hexadecimal digits and be terminated by a
  39 \fBNUL\fR
  40 byte\&.
  41 .PP
  42 \fBsd_id128_from_string()\fR
  43 implements the reverse operation: it takes a 33 character string with 32 hexadecimal digits (either lowercase or uppercase, terminated by
  44 \fBNUL\fR) and parses them back into a 128\-bit ID returned in
  45 \fIret\fR\&. Alternatively, this call can also parse a 37\-character string with a 128\-bit ID formatted as RFC UUID\&.
  46 .PP
  47 For more information about the
  48 "sd_id128_t"
  49 type see
  50 \fBsd-id128\fR(3)\&. Note that these calls operate the same way on all architectures, i\&.e\&. the results do not depend on endianness\&.
  51 .PP
  52 When formatting a 128\-bit ID into a string, it is often easier to use a format string for
  53 \fBprintf\fR(3)\&. This is easily done using the
  54 \fBSD_ID128_FORMAT_STR\fR
  55 and
  56 \fBSD_ID128_FORMAT_VAL()\fR
  57 macros\&. For more information see
  58 \fBsd-id128\fR(3)\&.
  59 .SH "RETURN VALUE"
  60 .PP
  61 \fBsd_id128_to_string()\fR
  62 always succeeds and returns a pointer to the string array passed in\&.
  63 \fBsd_id128_from_string\fR
  64 returns 0 on success, in which case
  65 \fIret\fR
  66 is filled in, or a negative errno\-style error code\&.
  67 .SH "NOTES"
  68 .PP
  69 The
  70 \fBsd_id128_to_string()\fR
  71 and
  72 \fBsd_id128_from_string()\fR
  73 interfaces are available as a shared library, which can be compiled and linked to with the
  74 "libsystemd"\ \&\fBpkg-config\fR(1)
  75 file\&.
  76 .SH "SEE ALSO"
  77 .PP
  78 \fBsystemd\fR(1),
  79 \fBsd-id128\fR(3),
  80 \fBprintf\fR(3)